Method of making dithiophosphates and compositions containing same



July 19, 1932, G. H. BUCHANAN METHOD OF MAKING DITHIOPHOSPHATES AND'COMPOSITIONS CONTAINING SAME Filed Feb. 18, 1930 SODA ASH MIXER TRAYDRYER KETTLE BLOW CASE STORAGE PDT ALCOHOL MILL WAZDJ FINES STORAGE )6TO VENT REFLUX CONDENSER Q V R O m A ALCOHOL STORAGE FROM AClD' BLOWCASE JACKETED I GLASS LINED REACTION KETTLE INVENTOR Gug H. Buchanan 8ATTORNEY F5 preferably using an excess of Patented July 19, 1932 UNITEDSTATES PATENT OFFICE GUY H- ZBUCHANAN, 01 WESTFIELD, NEW JERSEY,ASBIGNOR TO AMERICAN CYANAMID COMPANY, OF NEW XOBK,

N. Y., A CORPORATION OF MAINE Imon OF MAKING DI'IHIOPHOSPHA'IES ANDCOMPOSITION CONTAINING SAME Application filed February 18, 1980. SerialNo. 429,270.

The present invention relates to the manufacture of alkali metal saltsof dithiophosphoric acids and more particularly the salts of the oranicdithiophosphoric acids.

5 There as been described previously the manufacture of various or anicdithiophosphoric acids and the salts t ereof, which are used for variouspurposes, such as flotation reagents and the like. In the preparation ofthe salts of these acids, the usual method, of course, is to neutralizethe acid in solution with an alkaline material also in solution, withsubsequent evaporation of the water to obtain a solid product. Asidefrom the costly drying operation, the product so prepared is dithcult todry completely in view of the oily impurities usually contained in thecommercial acid. Dr ing the solution also results in loss of pro not bydecomposition and the color of the final product is affected.

It'is one of the objects of the present invention to prepare. the alkalimetal salts of the organic dithiolphosphoric acids in an economicalandsimp e manner, obtaining a dry, white product which is comparativelyfree from lumps. Such lumps as may be present are broken up easily withthe hands. Another object is to obtain salts and mixtures which arestable and which .are substantially non-deliquescent.

These and other objects are attained by neutralizing the dithiophoshoric acid with a dry alkahnecompound an alkali metal, the-alkali metalcompoun In the accompanying drawing constituting a part hereo Fig. 1illustrates diagrammatically substantially the entire process andapparatus;

Fig. 2 is a more detailed diagrammatic view of a portion of theapparatus; and

Fig. 3 1s a detailed diagrammatic view of another portion of theapparatus.

The production of the dithiophosphoric acidis carried out in reactionkettle 1 which is preferably a glass-lined, jacketed kettle rovided witha stirrer or tator 2, driven 5 suitable means 21. Using a kettle of a at100 gallon capacity, there is placed in ly been crushed to a maximumsize of about The manhole cover (not shown) is clamped down and 206 lbs.of ethyl alcohol from storage container 4 is slowly run into thekettlel. The cooling water in thekettle jacket must be so regulated thatafter all the alcohol is in, the final temperature of the mix is about40 C. The stirrer 2 is rotated during the course of the addition. Thekettle and contents are allowed to stand (from a source not shown) aboutand cool overnight. The next morning the mixture is heated to 90 C., andthe temperature kept there for 2% hours with agitation, after whichperiod, the mix is cooled down to room temperature. The crude acidsoprepared is condueted,to storage pot 5. If desired, a ortion of theacid may be left in the kettle or further preparation of acid. As shownin somewhat more detail in Fig. 2, the kettle is provided with asuitable reflux condenser 6 to prevent loss of alcohol orother materialsduring the reaction. The rocedure just described results in the prouction of about 400 lbs. of crude (86%) diethyl dithiophosphorie acidhaving a specific gravity of about 1.19.

Torepare the sodium salt of the acid, a

suitab e mixer 7 is charged with .200lbs. "of

soda ash 'from storage bin 8. This soda ash should be asdryas possibleandfree from lumps. Acid from the storage pot 5 is drawn into aluminumblowcase 9 and blown thence to feed pot 10. Thence it is run into themixer 7 by gravity through a suitable aluminum or similar tube (notshown). Ordinarily the first 100 lbs. of acid is added at the fullcapacity of the feed mechanism. Stirrers 11 in mixer 7 are operatedthroughout the addi tions of the acid. The second 100 lbs. of acid themixture becomes dark in color or tends to become sticky duringaddition-0t the acid, the

- are added more slowly and, in the event that sis a substantially dryThis mawhite powder. terial is preferably placed in a tray drier 12 anddried overnight at about 150 F. The dried product is screened inscreening device 13 to remove the lumps which are ground in a mill 14,the fines from 13 to 14 being sent to storage bin 15. The final producthas an iodine number. between 29.5 and-30.5 and is well adapted for useas a flotation reagent. It has a white color and does not formobjectionable lumps.

To obtain a higher ade product, it is sometimes advisable to a (1 about60% of the acid to the soda ash in mixer 7 and after a thorough mixingto remove the resulting product to drier 12 .or a similar drier where itis maintained at a temperature of about 115 F. for about twenty hours.The dried material is then returned to the mixer and the additional so40% acid is added slowly with stirring. The alternate mixing and d 'ngoperations may be multiplied to any desired de ee. The resulting productis a white or bu -colored powder containing a very small percentage 0gers. The material so prepared may be again sent to drier 12 and putthrough the succeeding steps in the process as previously described. Inthis method somewhat better elds are obtained and the product has aigher purity as well as other desirable characteristics.

While the preparation of sodium di-ethyl dithiophosphoric acid has beendescribed in detail, other alcohols or alcoholic bodies may be utilizedin reparing the corresponding organic dithiop osphoric acid by reactionwith phosphorus entasulphide. Thus we may prepare the i-methy di-lSOlilOyl, di-normal but 1, di-secon ary but i-amyl, diphenyl, '-eresyl,etc.,dithiop osphoric acids. As a neutralizing agent we may use any of thealkaline compounds of the alkali metals suchas potassium, sodium, orammonium carbonates hydrates, etc. The alkaline material is pre erablyused in excess and may bepresent to the extent of 200% in excess of thatnecessary to neutralizethe acid. The mixture of alkali metal salt of thedithiophosphoric acid with an excess of the alkaline material isparticularly valuable for use as a flotation re- L agent. This is partlydue ;to its hysical nature which permits storage, handling anduse withfacility and lack f decomposition.

lumps which can easily be broken with the fin- Also, in actualflotation, the presence of exv cess alkali assists materially thechemical action of the flotation agent. 1

Any suitable apparatus may be used in carrymg out the various steps ofthe process since the elements described may be varied at will, theexamples being given only for puroses of illustration.

Suitable changes in details of o eration and materials used may be madewit out departing from the spirit and scope of the invention, except asstated in the appended claims.

What I claim is 1. The process of preparing alkali metal salts oforganic dithiophosphoric acids which I comprises intimately mixin anorganic ditlll: ophosphoric acid with a so 'd alkaline alkali metalcompound by adding a portion of the acid to the compound, drying themixture, and adding the remainder of the acid.

2. The process of preparing sodium salts of di-alkyl dithiophos horicacids which comprises intimately mixing the acid with solid sodiumcarbonate in excess of the amount required for a complete neutralizationof the acid. J

3. The

process of preparing sodium salts of di-alkyl dithiophosphoric acidswhich comthe acid with solid proportion of not of that required forprises intimately mixing sodium carbonate in the more than 200% inexcess complete neutralization of the acid.

4. The process of preparing a sodium salt of di-ethyl dithiophosphoricacid which com: prises intimately mixing 100 parts by weight of di-ethyldithiophosphoric acid with 100 parts b weight of solid sodium carbonate,the aci being added in several portions with a drying step betweenadditions. p 5. Acomposition comprisin analkali metal salt of an or anicdithio osphoricacid and a' substanti quantity 0? an alkaline alkalimetal compo d.

6. A composition comprisinglan alkali metal salt of di-ethyl dithiophosporic acid d a substantial quantity of an alkaline alkali metal compound.

7. A composition comprising a sodium salt of an organic dithiophosphoricacid and a substantial quantity of an alkaline sodium compound.

8. A compfisition comprising a sodium salt of di-ethyl stantial quantityof so um carbonate.

9. A composition comprising a sodium ethyl dithiophosphate and sodiumcarbonate, the latter forming mixture.

of alkali metal salts of or phoric acids suitable as otation reagentswhich comprises intimatel mlxin an organic dithiophosphoric acid with aso id-alkaline alkali metal compound.

11. The process of preparing compositions 10. The process of preparincom 'tions an le dithiophosthiophosghoric acid and a sub-- the majorportion of the to the sodium carbonate of sodium salts of di-alkyldithiophosphoric acids suitable as flotation reagents which com risesintimately mixing the acid with solid sodium carbonate.

12. The processof preparin compositions of a sodium salts of di-ethyl di'ophosphoric acid suitable as flotation reagents which comprisesintimatel mixing di-ethyl dithiophosphoric acid wit solid sodiumcarbonate.

In testimony whereof, I have hereunto subscribed my name this 11 day ofFebruary,

GUY H. BUCHANAN.

